Relief valve for pumps



July., 29, 1930. y v E. J. WNDELL 1,771,975'

RELIEF VALVE FOR PUMPS f Filed sept. 24. 192'/v Pei-@ated July ze, 193elUNITED STATES EVEET Jf. WENDEILL, or WAYNE, PENNSYLVANIA l .RELIEF4vnLvE Fon Piiirs Y Appncauon'nied september 24, kr1927.v serial No,221,774. y Y

This inventionrelates to improvements inrelief valves for pumps, andWhile not limited in application is particularly useful in Connectionwith rotary gear pumps of the'Y 5 type used in fire apparatus'. 'i

lThe principal object of the invention is to provide a pressure'reliefvalve Whichshalll be smoothv and efficient 1n operation andv which shallprevent, by novel valve-control 10 ling means, the4 uncontrolledoscillationv of the valve which under certain pressure conditions is acommonfault of yrelief valvesofl 'v chamber28 in the casing, from ywhichchamber extends the pipe 15,so that in the present y this generalcharacter. f Y

'n Anotherl object of the invention is to pro- 1.; vide a relief Valveso constructed Vthat the po-` sitionV of the valve is accuratelyVdetermined' bv `the amount of excess pressure which is thefunction ofthe valve to relieve.

The invention further resides Vin certain: y

'.tothepressurefor'discharge sidey of the pump'f 7" 20 novel structuralfeaturesvand arrangements" of partshereinafte'r set" forth andillustrated' in the attached dravving5'which-gives,in moreV` v l wteasing 1 7 jalso includes Aa port 29,fromv which;`

or less diagrammatic form a sectional view of apreferred embodiment ofmy invention.'

2' 4With reference to the drawing,the device comprises a casing 1adaptedto be secured to the'casing of the pumpvitlifwhich the-de-y viceis'to be usedl and havingfpor-ts 2 and?) to be connected respectivelytothe discharge and suction'sides of the saidgpump.: Con; n nected withthe port 2, vis a chamber twvhiohv isy normally separated fro'machanibervv l'5,

with Whichl the port3'communicates,v ya" valve 6 movably;` mountedinf-the casing.4 rlhe valve '6 includes a'stem 7'Which slides in afguide8l inthe casing, and iat the opposite side 'a stem 9 terminating in apiston 10 which operates in/'acylinder l1 in the casing eX- tendingfrom'the; chamber 5f It Will be Lff noted that the piston 1Q is greaterindiameter i,

Vthan the 'valve' 6,12

.The outer endjof the'cylinder 11 closed:v Vbyca 'head' 12 havingtherein ports 13V. and $14 which communicate through pipes 15land 16y l5With pilot valves 17 andv 18 respectively.v The valve 17 comprisesacasing 19-having at-.qone' 'end ay port 21 andalsoatthisvend a "bushing522 Which'constitutesa seatfor a plunger r valve 23 `sl-idably mountedin the .Y 50 casing. Thevalve 23 visp-normally held toits `may passtothe drain.A A sor-een. 31 is pro- 7' vided across the port 21 toexclude fror'nthev 'normally connectedvvith 'ztlief discharge orpressure sidepf theA pump so .that-the saidv esL .on-the casing 19.Thefport 211When -the' valve 23 is open isfinjcommunication'with a: v

obstructed v vpassage' is provided betweenl thev port`1-21and the port13` in they head 12 and.'l theouteryend of the cylinder. 11.V Inoperaeqtion, the port 21; of' thei valve 17V is connectedl so tliat thel outerface `ofthe valve 23 :iscon-` n tijnuously subject-ed t'o pump pressure.Y E The any leakage'of liquid past Ytlieiplunger..23Vl

valve any solidforr` foreign material .that -Y might interferevWith-"the proper .seating-of, the valve 23 or'dis'turbthernormaloperation'v ofthevalve, 'j l c lThe valve 18 comprisesa casing32fhaving` .an'intake port 33 and :a 'discharge port- .34,v .bothcommunicating Witha chamberv 35.". A- @plu'nger' valve 36 operatesinfthecasing and A- normally seats'at '37,Ktherebyshutting` offthe;

intalep'ort 33 from' the chamber 35gand from;V the Vdischarge port vThe:casin'gfalso in-y cludes ay port '38 which is closedz'by the outer endvof the plunger A36,1`arj1dthis 'port 38 isi 0 outer'. end ofA theplunger 36 is= continuously subjected to pump .pressure which?tends .tohold. thexvalve to its seat.;v In "this instance alsoa Sui-table screen-39 -is provided'ov'erfthe port 38 togexclude' foreig1-materialVv from Ythe` pumpcasing.-" Acting'ju'pony the plungerl36" c in -ippositionitothepump l,pressureisf a ond plunger 42, the springs and the lastnamedplunger being mounted in a chamber 43 formed by a casing par-t 44threaded on an extension of the casing 32, as clearly 1llustrated.Obviously the pressure of the springs upon the plunger 36 may be variedby adjusting the casing part 44 upon the cas-V ing 32. Provision is alsomadethrough a passage 45 for bypassing `any leakage of liquid past theplunger 36 tothe discharge Vport 34, which is connec-ted with the drain.

The intake port 33 is connected through the pipe 16 with the port 14 inthe cylinder head 12 and with the outer end of the cylinder.

Under certain conditions, it is desirable to l provide positive meansfor holding the valve of Which the shaft may beturned inwardly againstthe outer end of the stem 7, therebyV to hold'the valve 6 positively` toits seat. As

indicated at v51, the stem 46 is suitably packed to prevent leakage.Also -in order to prevent the trapping of liquid in the space-betweenthe outerend of the valve stem 7 Vand the 1nner lend of the shaft 46, I.provide in the said stem 7 passages" 58 which extend `tromthe outerrendof the stem to the sides thereof Within the chamber 4.

-Under certain circumstances also'gufell'un-` derstood by thoseacquainted with .the art, itA

may be desirable to hold the valve-6 open by positive Vand manuallyadjustable means.V

accordingly provide in .the-cylinder head 'l2- Vmeans for supporting ashaft 53,this shaftbeing threaded in the head asV indicated at 54 andbeing adapted tobe turned in through the medium of. a hand Wheel 55 on`the outer projecting end ofthe shaft against the outer tace of thepiston 10 Vto therejby-orce-the latter inwardly and the valve 6 from itsseat. Suitablepacking means is provided atn56 to prevent-.leakagefromthe. cylinder llfpast the shaft 53. v

In opera-tion, the pressures of the springs 24 and 41 are adjusted toapproximately Vthe `mairiniiunpressure at .which it is desired tooperate .thepurnpv In the normal operation therefore, as soenastheipressure in the pump increases to .a point above :the normaloperating pressure, lthe valve 2S will-be forced open, .therebypermitting application of pump pressure through :thefpipenl totheouter-face of the piston 10. At this peint, it Willbenoted that the pumppressure is also acting against the-plunger 36 of the valve 3 2 toretain this'valvefin thenormal closed position, as illustrated, so tliat.the port 33 l and `accerolingly the lport 14 Vin the cylinder. Yhead'12fiseifectively closed. Theoi'itertace of the valve 6 is alsosubjected to pump pressure, but the piston 1() being ot greater areathan the valve 6, the pressure applied through the port 13 as describedwill cause a movenient oftl the piston in the cylinder and the openingof the valve 6. This movement. continues until the opening of the valve6 provides a bypass between the discharge and suction sides oi the pumpthrough the chambers 4 and 5 suiiicient to relieve the abnormalpressure, 'at which point the valve 23 again closes, and so long as .theconditions Which cause this abnormal pressure exist, the valve 6 Willremain open just suiiiciently fai-'to relieve the pressure, theoperation of the pump remaining otherwis'eat normal. l from any causethe pump pressure againexceeds normal, the valve 26 will again open andcause a further movement of the piston 10 and a consequent: iurtheropening oi' the valve 6 until the pressure decrease allovvs the valve 23to close, at Which point the movement of the piston stops, .the` valve 6then being open just sufficiently far .to relieve the abnormal pressure.

if the pressure falls below normal, the. pi-. lot valve y2. comes intoplay. By reason of the falling Vpressure on the outerend of the valve36, the spring 41 opens the valve 36, thereby providing a direct passagebetween the ports 33 `and 34, and a direct line of discharge from theouter end of the cylinder l1 to ,theV drain.

pressure acting` on the inner face of the piston iorces the pistoninwardly until the valve ,6 is closed or until the amount of the,bypassed iluid is such .as to .bring the pressure vpressure changedevelops. Y

.By this arrangement and by use of the two pilot valves as describedabove, I have Ven.-V

The pressure on the outer face. of tljiegpistonV being thus reduced, thepump' tirelyeliininated vibration of the valve 6 and have provided arelief device which is smooth and entirely eiiicient'in operation. A

VInbrder to assist the operator in'setting V.jthe.apparatus for any*vpredetermined desir-v able pump pressure, the relatively Vmoving partsof the pilot valves maybe calibrated to "if Y indicate the pressures of'the springs 24 and 41 ior anyl given position-of the casing parts27c1244 .ivith respect vvtovthe.casings proper. lhere, as in certaintypesor" operation, it is Y essential that the valve 61be tightly-closed,-

this can be accomplished manually by means oithe lock wheel 49,:and thevalve; 6 maybe Y positively opened and heldin the"A open positionlwhen.desired Wheel 55.@

lelailm:

f 1. n.adevice'foiautomatic-ally Inai'nt-ain-Vv by :means ofthe Vhand"-a constant pressure dierence between tivo: points et a-fpressure`fluid'-e'oncluit, the

y side of said bypass duct, a kvalve normally closing. said intake portand adapted to open automatically when the pressure in the intake sideof said duct increases beyond a predetermined point, a valve normallyclosing the discharge port of said cylinder and op-` eratively connectedwith the intake side ol the bypass duct whereby the valve is normallyheld closed by pressure in said duct, and means whereby rthe lattervalve is automatically opened when the pressure in the bypass Yfallsbelow a predetermined point.

2. In a device vfor automatically maintaining a constant-pressuredifference. between two points ot a pressure fluid conduit, thecombination with a duct vadaptedto constitute a bypass between saidpoints, a valve controlling said duct, and means including a pair ofpilot valves individually operatively connected with` the intake vend ofsaid duct tor actuating the valve automatically to maintain apredetermined pressure at the intake end ot said duct. Y

3. In a device for automatically maintaining a constant pressuredifference between two points of a pressure fluidconduiathe combinationwith; a duct adapted to constitute a bypass between said points, of avalve controlling said duct, a cylinder, a piston within said cylinderoperatively connected with the valve and arranged so that-.one side ofthe'piston is subjected to the pressure of -the intake end of saidbypass when said valve is opened, means for subjecting the opposite sideot the piston to the pressure in the intake end of said duct including acontrol valve adapted to open only when the said pressure exceeds apredetermined normal, and means for relieving the pressure in thecylinder to permit the piston to move in a valve-closing directionincluding a valve operatively connected with the intake` side of theduct so as to be closed when the pressure in the said intake is atorgreater than the normal and adapted to automatically open when thepressure decreases below the normal.

4;. In a device for automatically maintaining a constant pressuredierence between combination with a pair of chambers adaptedrespectively to be connected to saidpoints,y

port connecting said chambers, and a valve operating in the Chamberconnected to the said point of higher pressure and adaptedv point oflower pressure, a piston in said cylinder connected with-the valve,intake and discharge ports in the outer end of said cylinder, means.connecting the intake port with theA chamber of higher pressure and thevdischarge port with an exhaust, and a plurality of valves controlled bythe pressure at the said point of higher pressure and controllingthemselves the opening and closing fot said intake and discharge ports.

5. In a device for automatically maintaining a constant pressurediierence between two points of a pressure fluid conduit, the

combination with' a duct adapted to consti-` tute a bypass between saidpoints, of a valve adapted to close said duct, and means for actuatingthe valve to control the relative pressures at the ends of said bypassincluding a pair of pilotvalves, one of which isaected by an increase inthe pressure at the point of higher pressure to cause the bypassvalvevto move open, and the other of which is affected by a reduction insaid pressure to cause the bypass lvalve to move-closed.

Evitar J. WENDELL.

two points of a pressure fluid conduit, the

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